As auto three-dimensional image display apparatuses (hereafter referred to as three-dimensional image display apparatuses as well) which makes it possible to view a three-dimensional image without glasses, the multiview scheme, the dense multiview scheme, the integral imaging scheme (II scheme), and the one-dimensional II scheme (1D-II scheme: parallax information (pixel values of a parallax image) is displayed only in the horizontal direction) are known. These have a common structure that optical openings represented by a lens array are disposed on a front face of a flat panel display (FPD) represented by a liquid crystal display device (LCD). The optical openings are disposed at constant intervals, and a plurality of FPD pixels are assigned to each optical opening. In the present specification, a plurality of pixels assigned to each optical opening pupil is referred to as pixel group. The optical opening corresponds to a pixel of the three-dimensional image display apparatus, and a pixel seen via the optical opening is changed over according to the viewing location. In other words, the optical opening behaves as a three-dimensional image displaying pixel which changes in pixel information according to the viewing location.
In the three-dimensional image display apparatus having such a configuration, pixels on the FPD are finite. Therefore, there is a limitation in the number of pixels forming the pixel group as well. For example, there are pixels in the range of 2 to 64 pixels per direction. Especially the case of two pixels is referred to as two-view scheme. Therefore, it cannot be avoided that the range (viewing zone) in which a three-dimensional image can be viewed is limited. In addition, if a viewer deviates from the viewing zone to the left or right, it cannot be avoided to view a parallax image of a pixel group corresponding to an optical opening which is adjacent to the original optical opening. Since light rays viewed by a viewer at this time is a three-dimensional image formed by light rays passed through an optical opening adjacent to the original optical opening, the light ray direction does not coincide with parallax information and distortion is contained. Since the parallax image is changed over according to a movement of the viewing location, however, this is also seen as a three-dimensional image in this case as well. Each parallax image corresponds to a multiple viewpoint image picked up by using the display plane as the projection plane from a location of a converging point of light rays generated at a viewing distance L. In some cases, therefore, a zone where the three-dimensional image (overlapped multiple image) containing the distortion is seen is called side lobe.
A method of controlling the viewing zone of the auto three-dimensional image display apparatus by adjusting the number of pixels included in pixel groups assigned to optical openings is known. According to this technique, the number of pixels included in pixel groups is set equal to two values: n and (n+1) where n is a natural number of at least 2, and the appearance frequency of pixel groups each having (n+1) pixels is controlled.
In a transitional zone from a proper viewing zone to the side lobe, however, parallax images on both sides of a boundary between pixel groups are seen in a state in which the arrangement of parallaxes is inverted. It is known that consequently a phenomenon called pseudo-stereoscopy occurs and an image inverted in unevenness is viewed. Or parallax images on both sides of the boundary between pixel groups are seen at the same time. It is known that consequently videos to be seen at viewpoints which are originally different are seen overlapped resulting in a multiple image.
As one of counter methods against such an overlapped multiple image in the multiview three-dimensional image display apparatus, a technique for making it hard to perceive the overlapped multiple image by replacing a parallax image corresponding to a viewing zone boundary with an excessively smoothed blurred image is known.
As one of countermeasures against the problems described above caused by the overlapped multiple image, a technique of informing the viewer that the side lobe is not a proper image by, for example, displaying some warning image in a transitional zone from the viewing zone to a side lobe so as to be sensible although the sense of incongruity cannot be reduced is known.
It is known that a stripe-shaped breakup image is generated besides the above-described problems when the above-described method of controlling the viewing zone is used. As a countermeasure against this, a technique of suppressing the stripe-shaped breakup image by selecting a pixel on one side determined by whether it is located on the left or right side of the screen center, from parallax information of pixels located on both ends of a pixel group having (n+1) pixels, and mixing the parallax information of the pixel with parallax information of at least two pixels located at a distance of n pixels in a pixel direction adjacent to the pixel is known.